Display devices are ubiquitous and are present in numerous devices ranging from telephones and computing devices, to televisions, control devices, individual microdisplays for placement near the viewer's eye and the like. Most displays today are based on flat panel technologies, such as LCD (Liquid Crystal Display), LED (Light Emitting Diodes), including the organic variety known as OLED, plasma, and the like. Polychromatic displays of this type use a plurality of individually addressable monochromatic pixels, commonly RGB—Red, Green, and Blue—to provide an illusion of ‘true-color’. As long as the distance between the individual colored pixels is small, the human mind merges the individual pixels. However, such mixing requires a viewing distance from the display device and, generally, the larger the display area the more noticeable the effect of the three separate colors in a pixel. Moreover, while weighing but a fraction of the weight and consuming but a fraction of the power of old cathode ray tube displays, current displays often consume significant energy and still require significant bulk. Such displays also commonly utilize a plurality of expensive transparent conductor material as electrodes for energizing a specific location within the display.
Lately, stereoscopic displays appear in many devices. Such displays provide an illusion of three dimensional objects and are colloquially known as ‘3D displays’, or 3 dimensional displays. It is noted that those devices are not truly three dimensional but create the three dimensional illusion at the viewer's brain, and in these specifications the terms 3D, three dimensional, and stereoscopic will be used interchangeably. 3D display systems provide two streams of video, separating the flow of each of the video streams to a different eye of the viewer. Oftentimes this is carried out by controlling shutters located in eyeglasses worn by the viewer. In some other embodiments, light switches, slots, and other effects are placed in front of the television screen. A common method for obtaining the 3D displays utilizes ‘passive’ eyeglasses which separate the image for each eye based on light polarization. By way of example, a first image may be displayed with horizontal polarization while a second, slightly displaced image is displayed using light at a vertical polarization. The viewer wears glasses with matching polarization for each eye, thus allowing each eye to see only the image which is directed to it. In certain embodiments, circular polarization is utilized to allow a 3D illusion even when the user tilts the head. Active 3D systems, i.e. the systems that use controlled shutters in the eyeglasses, provide a better viewing experience, but the eyeglasses require power and are heavier and more expensive than the passive eyeglasses based systems.
Light is one form of radiant energy which may be considered as an alternating electromagnetic radiation at very high frequency. Humans perceive different light frequencies as different colors, and there is a large amount of radiation that is not perceived by humans, generally known as UV (Ultra Violet) and IR (Infra Red), and the term light will be extended thereto. Visible light ranges generally between 760-390 nm and corresponds to the peak intensity of solar radiation transmitted through the atmosphere. Long wave infrared radiation ranges from the extreme far end of 33 μm (10 THz; millimeter radio waves) to about 760 nm and solar radiation contains a significant amount of total energy below about 3 μm. It is clear, therefore that radiant energy as used herein covers a very broad spectrum of radiation. Clearly specific applications would be required to cover only portions of this spectrum. By way of example, for solar energy applications the spectral range of interest will likely be a spectrum containing most if not all of the solar spectrum available at the location where the solar cell is to be deployed, or the portion thereof which is economically used by the device at hand typically 3 μm to 300 nm. The spectral range of interest for most display devices is within the visible light, even if some special applications demand extending the spectral range. In some applications a specific wavelength may be desirably attenuated, such as by way of example reduction of blue light for pilot related devices. Yet for devices directed to heat energy recovery, it is likely that only the infra-red portion of the spectral range is of interest. Similarly, the spectral range of interest may be applicable to certain portions of a device. By way of example a device may be directed to a broad spectrum, but portions thereof may be directed to a narrower spectrum, and the spectral range of interest is thus limited to the range of interest of the portion of the device. By way of a non-limiting example, a television may occupy a display portion that utilizes CRTR's as described below and additional emissions such as audio outputs. The spectral range of interest of the CRTR may only extend to the visible range, even if the device as a whole includes the aural range as well. It is seen, therefore, that the application at hand determines the spectral range of interest for which an apparatus utilizing the invention is directed to.
Therefore, the spectral range of interest is defined herein as relating to any portion or portions of the total available spectrum of frequencies which is being utilized by the application and/or apparatus at hand, and which is desired to be detected and/or emitted utilizing the technologies, apparatuses, and/or methods of the invention(s) described herein, or their equivalents.
The term “stationary resonance condition” should be construed as relating to a situation in a waveguide where the frequency of the guided wave is sufficiently close to the local cutoff frequency of the waveguide, such that the guided wave reflects repeatedly between opposing surfaces of the guide. The corresponding energy velocity along the waveguide propagation axis is significantly lower than the speed of light in the bulk material of the waveguide and approaches zero at the stationary resonance condition. Notably, complete stationary resonant condition is an ideal limiting case which is almost never achieved.
The term Continuous Resonant Trap Refractor (CRTR) should be construed as relating to a waveguide having a tapered core, the core having a base face and a tip. The larger face of the tapered waveguide core will be generally referred to as the aperture, and the smaller face, or point, will generally be referred to as the tip. Light travels along the depth direction extending between the aperture and the tip, however the light may travel towards the aperture; or away therefrom. For the purposes of these specifications, the depth increases from the aperture towards the tip such that larger depth implies greater distance from the aperture. The term ‘tapered core waveguide’ requires only that the waveguide core be tapered, and the overall dimensions or shape of the CRTR may be of any convenient shape.
A distance from the aperture along the depth dimension, at which the width of the waveguide in at least one dimension would be the critical width, which will block light of a given frequency from advancing further down towards the tip, is referred to in these specification as ‘emission depth’ for this frequency. The emission depth is also the depth where energy of a given frequency injected to the CRTR via the cladding would best couple to the CRTR core and travel towards the aperture. The width of the CRTR core which causes the energy to be emitted through the cladding or is coupled through the cladding from outside the CRTR for a wave of a given frequency is termed ‘emission width’ for that wave. Such emission is termed ‘cladding penetration state’. When polychromatic light is admitted through the CRTR aperture, lower frequency waves will reach their emission depth before higher frequency waves. As the wave energy departs the CRTR at its emission depth, lower frequency light would penetrate the cladding and exit at a shallower depth than higher frequency light. Thus, the CRTR will provide spatially separated spectrum along its cladding. In addition, the CRTR refracts the spatially separated light away from the axis of the CRTR extending from the aperture toward the tip. Conversely, light coupled to the core via the cladding at the emission depth will travel from the emission depth towards the aperture, and different frequencies coupled through the cladding will be mixed and emitted through the aperture. Coupling light into the CRTR core from the cladding will be related as ‘injecting’ or ‘inserting’ energy into the CRTR.
Therefore, for a given CRTR spectral range of interest Si, ranging between λmax to λmin, which represent respectively the longest and shortest wavelengths of the spectral range of interest as measured in the core material, wherein λ′ is at least one wavelength in Si, the dimensions of a CRTR taper are bounded such that                a. the aperture size ψ must exceed the size of one half of λmax;        b. the CRTR core size must also be reduced to at least a size which is smaller than or equal to one half of wavelength λ′.        Thus the CRTR dimensions must meet at least the boundary of{ζ≦λ′/2<λmax/2≦ψ}        where the CRTR sizes defined above relate to a size in at least one dimension in a plane normal to the depth dimension. It is noted that certain wavelengths in Si may not meet the condition b. above and in such cases all energy for which the wavelength λ′<2 ζ is transferred into or out of the tapered waveguide vertically through a truncated tip. It is noted that for a dielectric clad waveguide the effective width is slightly larger than the physical width due to wave penetration into the cladding, as is well known in the art, and the dimensions, ζ and ψ account, in this construction, for the waveguiding effects of the cladding.        
Cladding penetration may be caused by the wave approaching stationary resonant condition or when the wave reaches a critical angle which depends on the core/cladding interface. In certain embodiments cladding may be removed at a predetermined depth (core width) to achieve desired propagation characteristics.
CRTR's were first described in U.S. provisional patent application No. 61/701,687 and later in more detail in U.S. provisional patent applications No. 61/718,181, and 61/723,832, and in non-provisional U.S. patent application Ser. No. 13/685,691 to the present inventors. All the above mentioned patent applications are incorporated herein by reference in their entirety.
There is therefore a clear and heretofore unanswered need for better technology, devices, and methods of manufacturer which will solve the shortcomings of the known art for displays in general and also for stereoscopic 3D displays.